Building codes include fire protective provisions for all types of construction to prevent fires and mitigate damage. For example, building codes typically include detailed recommendations and/or requirements regarding structural designs, assemblies, sprinkler systems, smoke detectors, and other factors related to igniting and containing fires in a building.
Wood-based I-joists are used in approximately 50% of US single family homes, and in particular for raised floor and first-floor-over-basement construction. For finished basements that are built with I-joists, one layer of drywall covering the I-joists typically meets the fire provisions of the building code with respect to the use of I-joists. However, with unfinished basements where the I-joists are not covered by dry wall, builders need cost effective solutions for meeting the I-joist fire protective provisions of many building codes.
One option for meeting fire protective provisions in unfinished floor-over-basement construction is to use solid sawn construction materials. However, solid sawn construction materials suffer from a relatively high incidence of call backs.
Another option is to coat I-joists with fire resistant coatings. Such coatings are typically liquid materials that are sprayed, brushed, or painted on I-joists, and the coating may harden to some degree after application. Examples of such coatings are described in U.S. Pat. Nos. 5,968,669; 6,245,842; and 8,458,971, and U.S. Published Patent Application No. 2015/0111052. However, although such coatings may perform well on I-joists in some fire resistance tests, they do not necessarily perform well on others. For example, a coating that is relatively non-combustible may prevent the spread of a flame along its surface (in accordance with, e.g., ASTM E2768), but may do very little to protect the substrate from heat degradation (e.g., as required by ASTM E119). Conversely, a coating that rapidly expands when exposed to heat or flame may not prevent a flame from traveling along its surface. Another issue is that many of the flame resistant coatings are applied in the field, which is laborious and time consuming.
Ultimately, the construction industry needs improved and cost effective ways to enhance the fire endurance properties of building products.